1. Field of the Invention
The present invention relates to the in-plane uniformity of a semiconductor substrate after a step of processes in the production of a semiconductor device. Specifically, the present invention relates to an in-plane distribution data compression method, an in-plane distribution measurement method, an in-plane distribution optimization method, a process apparatus control method, and a process control method.
2. Description of the Prior Art
Japanese Unexamined Patent Publication No. 2002-184733 discloses a conventional measurement method, which is described herein with reference to the flowchart of FIG. 30.
The measurement method comprises the steps of: performing a first process on a first substrate; and performing a second process on the first substrate or a second substrate, wherein a correlation function for each of in-plane positions is obtained as data of the difference among a plurality of process steps for each of in-plane positions based on the in-plane distribution data for the in-plane position on each of the substrates which are the results of the plurality of processes, the in-plane distribution characteristics of the substrate under a desired process condition is calculated from the correlation function, and the substrate is processed based on the in-plane distribution characteristics.
In the conventional measurement method, one-dimensional measurement is performed to evaluate the distribution from the wafer center to the wafer edge. This has been commonly conducted because of an empirical fact that the in-plane distribution exhibits a substantially concentric distribution. Another reason for the one-dimensional measurement is that, in the case of two-dimensional evaluation, it is necessary to quadratically increase the number of evaluation points as the radius of the substrate increases, which is not required in the one-dimensional evaluation. Thus, in the conventional method, it is necessary to select fine one-dimensional (linear) measurement or rough two-dimensional measurement according to the purpose of measurement. In the case of one-dimensional measurement, even if the in-plane distribution is concentric, the center of concentric circles is off the center of the substrate in many cases. Therefore, accurate evaluation cannot be achieved.
In the case where two-dimensional measurement is carried out for the purpose of accurate evaluation, the measurement has to be conducted at an enormous number of measurement points and accordingly requires an enormous length of time. Furthermore, it is necessary to store an enormous amount of data resulting from the measurement, and therefore, a large capacity storage device is required.